Question

a group of tourists on a weeklong bus tour of a european country experienced an outbreak of norovirus. the group had followed a consistent meal time pattern: each morning they had breakfast together in whichever hotel they had stayed from 6:00 a.m. to 7:00 a.m., stopped for lunch from 1:00 p.m. to 2:00 p.m., then had dinner together either at the next hotel or at a restaurant at about 7:00 p.m. the incubation period for norovirus is about 24-48 hours, with a median of about 33 hours. on which day and at which meal was exposure most likely?

Answer 1

Explanation:

Subtracting 24 hours (the minimum incubation period) from the time of onset of the first case puts you in the April 20 Dinner interval. Subtracting 33 hours from the median case (which occurred in the 4-8 AM interval) on April 22), puts you in the April 20 4-7 pm interval, near both lunch and dinner that day. While the minimum method points to dinner on April 20, thorough investigators would probably investigate possible exposures at lunch that day, too.